Combining finite element and finite volume methods for efficient multiphase flow simulations in highly heterogeneous and structurally complex geologic media

The permeability of the Earth's crust commonly varies over many orders of magnitude. Flow velocity can range over several orders of magnitude in structures of interest that vary in scale from centimeters to kilometers. To accurately and efficiently model multiphase flow in geologic media, we introduce a fully conservative node‐centered finite volume method coupled with a Galerkin finite element method on an unstructured triangular grid with a complementary finite volume subgrid. The effectiveness of this approach is demonstrated by comparison with traditional solution methods and by multiphase flow simulations for heterogeneous permeability fields including complex geometries that produce transport parameters and lengths scales varying over four orders of magnitude.     

论藏品信息

藏品信息是博物馆藏品工作的新课题。本文从宏观的角度,分析了藏品信息的意义、要素、结构、分类、著录规则和标准化等一系列问题。     

Geochemical analysis of Late Classic and Post Classic Maya marketplace activities at the Plazas of Cobá, Mexico

Abstract

Lines of evidence for ancient exchange plazas may include trade routes and trade artifacts, urban open space near public structures, and rock alignments denoting market stalls, but regular patterns in soil chemical concentrations also point to marketplace use. We applied geochemical and geospatial analysis of the floors of the main Plaza of Group B and Plazas A, H, and J of Group D at Cobá, Mexico, to discover the chemical residues of phosphorus (P) and metals associated with the exchange of foodstuffs and mineral workshop items that may have been marketed there. The patterns of chemical residues in the floor of the Group B Plaza suggest ritual activities while the linear, parallel patterns of elevated Mehlich phosphorus and chelate extractable zinc concentrations in Plaza A support the hypothesis of market exchange at that location. Plaza H is associated with several Postclassic buildings, including the Pinturas Structure D-33. During the Postclassic period, Cobá had lost much of its population, though chemical residues from Plaza H are congruent with marketing. We argue that Plazas A and H were not permanent marketplaces but rather multi-purpose locations that also hosted large ceremonies.     

Early Cambodian gold and silver from Prohear: composition,trace elements and gilding

Rescue excavations in Prohear, southeast Cambodia, recently saved the last untouched graves of one of the richest prehistoric sites in Southeast Asia. Many Iron Age burials dating from the 2nd century BC to the 1st century AD contained gold and silver ornaments so far unknown from archaeological contexts together with indications for the presence of an immigrated elite. A first selection of 59 objects were analysed by LA-ICP-MS to obtain detailed information about the composition, as well as minor and trace elements. The majority of the ornaments consist of electrum and auriferous silver with low copper concentrations, and two main groups indicating different alluvial gold sources can be distinguished by different concentrations of Pt, Ir, Bi and different Pd/Pt ratios, one group being related to rich burials with non-local features. The SEM and EDX analyses of four objects revealed two different gilding techniques observed for the first time in Southeast Asian artefacts: foil-fusion gilding, related to special Ag–Au–(Cu)–Sn alloys containing up to 4% tin, and depletion gilding.     

Raw materials for medieval to post-medieval Tuscan glassmaking: new insight from LA-ICP-MS analyses

LA-ICP-MS analyses were performed on a set of Tuscan (post) medieval archaeological glass finds dated to the 13–16th century in order to quantitatively determine the trace element contents. The results are used for defining and distinguishing several compositional groups. The trace element data are consistent with the distinctions obtained by considering the major element data determined via quantitative SEM-EDX, but allow to obtain new insights into the nature and quality of the silica sources employed and the presumed method of ash purification.     

甘肃马鬃山区石板墓初步研究

2004年7月下旬至8月底,西北大学文化遗产与考古学研究中心和甘肃省文物考古研究所联合在甘肃肃北县马鬃山区进行了为期一个月     

《桃花源记》以桃命篇论

陶渊明诗文喜用菊、松、柳等托物寄情,然在《桃花源记》一文中,却为何舍熟就辟,取桃与桃花意象来命题立意？对此,学术界讨论较少。本文将从民俗信仰和文学的比兴手法两大角度来讨论该问题。     

上海松江区广富林遗址良渚时期人骨微量元素的初步研究

近几十年来,古代人群的食谱研究已经成为现代科技考古学的一个重要组成部分,也是当前国际科技考古学研究领域的一项前沿性课题。人类骨骼的化学元素分析为重建古代居民的食谱提供了大量信息。采用电感耦合等离子发射光谱仪(ICP-AES)对上海松江区广富林遗址良渚时期出土人骨中的Ba、Ca、Mg、Mn、P、Sr、Zn等7种化学元素测定的结果显示:发达的稻作业为该组居民提供了充足的植物性食物;而水网密集的周边环境同时又为该时期居民提供了丰富水产品,从而极大地补充了其蛋白质的摄入。     

Bone chemistry and the reconstruction of diet: Strontium discrimination in white-tailed deer

Studies of the relationship between the strontium content of human bone and past diet are still in an experimental stage. Because of the low frequency of carnivore remains at most archaeological sites and the absence of information on local strontium levels, it has been difficult to (1) estimate dietary intake for a prehistoric population, and (2) to compare prehistoric populations from spatially disparate areas. However, examination of strontium/calcium ratios in a modern herbivore may help to alleviate these problems. Bones from modern white-tailed deer (Odocoileus virginianus) were compared with deer diet in Wisconsin. An observed ratio between deer bone and diet in terms of a strontium/calcium index was calculated at 0204, which compares favourably with observed ratios reported for other mammals. Prehistoric white-tailed deer are used in the analysis of two Late Archaic sites in the midwestern U.S.A. The strontium levels in deer can be used as a baseline for comparison between sites. The prehistoric subsistence patterns are generally comparable, with hunting accounting for the bulk of the diet.